Data Interface for Amateur Radio

It's not so long ago that, curious about PSK-31, I figured-out that I could receive by sticking headphones to my PC's microphone, and send by sticking the rig's microphone to the PC's speaker.  It worked a treat to get me into the digimode, but it's hardly ideal.

So, round and round the internet I went, looking for anything that might distill into a sensible consensus on which data interface might be any good.  I think at this point I should invent the Rowlands Rule: the internet is a place for everybody to shout their opinion, and shout others' down; thus, no consensus is possible.

I had recently downloaded HRD, a fine package that carries an advert, or link to G4ZLP's web site, this being Neil, who makes digital interfaces by hand (you can, reassuringly, see where pencil marks have been made to guide the drilling of the holes for cable connections to be made!)

G4ZLP's DigiMaster Datalink interface receiving WSPR at the MW1CFN station.

I decided, after a bit of looking around, and wanting to do my bit to support homegrown enterprise, that I'd go for Neil's DigiMaster Datalink interface.  This comes in at an astonishingly good price of £69.99, well below the price of interfaces sold by the big outlets, and it doesn't need any jumpers to be bought or installed, just the appropriate PC-rig cable, another £8 or so in my case.

So, mindful that I'm not much of a computer nerd, have very little patience and no electronics knowledge to speak about, how did it go?

Well, 24 minutes after the postman gave me the box, two cables were connected up and I was sending WSPR signals out across the world.  After a few weeks of using the interface flat out on WSPR and PSK-31, and exploring other modes, I can honestly say there are no issues with Neil's box of tricks at all.  A very minor gripe, which probably applies to other interfaces as well, is that occasionally, there is a need to tweak the output level, which seems to me to drift a tiny bit, possibly with temperature, I'm not yet sure.  Maybe it's just my green-behind-the-ears-ism!

So, a big hit, and without having any link to Neil at all other than as a satisfied customer - of whom he seems to have very many - I'd recommend you get hold of one of his interfaces, which come in a variety of levels of complexity and capability.

Very nice work, Neil!

Update: 1 Year On.

Well, the old box has sent thousands of data messages across the world over the past year.  Sadly, on its first anniversary, Neil's interface decided to develop a fault.  It seemed to wake up to software using CAT control, but not always those (such as PSK/RTTY) using the data cable alone.  The TX/RX LED couldn't decide what mode it should indicate.  It appears to be an IC problem, but I have no ability in electronics. Neil also hasn't seen the problem before.

I've ordered another unit and cable, and Neil is still responding to emails very promptly.  The old unit is happy once it's had a few test signals passed through it, but it's a bit dicky on PSK (using DigiPan.)  It's surprising it gave up within a year, but put in perspective, I operate heavily every day, so compared to the weekend user, it would probably have lasted several years.  I don't think it's excessive to replace a £59.99 interface every year or so, given the fun and DX entities it provides. I still recommend the unit, certainly.

New unit arrived within two days of placing an order, back to transmitting like mad within seconds of plugging it in.  Thanks Neil!

Where are the Regulators?

Amateur radio is, in concept, a self-regulating service that doesn't often include heavy-handed state involvement.  That, to many, is the way it should be.

But when that self-regulation fails, what then?

I write this morning as, for the second time this week, some idiot or other is busy sending a whopping signal over the WSPR frequency, rendering that mode utterly devoid of any but the most powerful signals.

Why not shout louder?

Those keen to wipe out others' activities will say 'ah, but there is no such thing as a reserved frequency for any mode, so shut up!'  That's the attitude of the insensitive and uninterested in the genuine spirit of amateur radio.

To be fair, competitive, stamp on all others attitudes are in fact encouraged by the very societies that otherwise see it as their Very Important Duty to protect the bands.  DX awards, contests, it's all very macho, aimed at making the individual the most important thing, not the manner in which he operates or how he respected others.  Inevitably, many amateurs come to believe that they may do whatever they want to fill their logbook.

A good idea.  But is it really working?  I don't think so.

This is a very sad state of affairs, and I can't see things getting any better.  Listen to a pile-up.  Maybe record it and listen to it a few days later.  Is this what attracts youngsters to the hobby?  Listen to the digital parts of the spectrum.  Hear how everything is played over everything else, because their signal is more important than somebody else's, it seems.  Is that attractive to newcomers?

Self-evidently, the overwhelming domination of the hobby by retired white men is doing the hobby no favours at all.  In the words of the latest RSGB report "it's difficult not to conclude that, in the past ten years, our membership has aged by ten years."  That's a polite way of saying: in another 15 years, those societies are dead in the water.  The hobby would seem to be in the same boat.

The societies have a moral duty to investigate how the bands can be better policed and how enforcement can be ramped up, especially across national borders because, often, it is only from afar that you can hear those responsible.  Something akin to a radio 'Interpol' is required, and required urgently.

The future for amateur radio if we carry on like this...

So, next time you find yourself shouting down the mic in order to be heard by someone far away, just remember that you are as far away and exotic to him as he is to you.  You can make it another day.  There's probably someone more interesting a few kHz down the band. 

Be happier you didn't follow the crowd, didn't just add to the shouting mess, and that you took pride in how you operate. 

There should be an award for that.

Friday Was WSPR Day...

WSPR is a peculiarly fascinating digital mode. You need do little more than check your antenna is still standing and that the ALC isn't kicking in as the rig and PC attend to themselves quietly in a corner.

I find WSPR satisfies that endlessly-burning question in me: where is my signal getting to? I was never interested in contests, just where, how, and why my signal gets to where it gets.

WSPR lets you do this without calling CQ 2,800 times in a day, and gets you a real, numerical signal report that is much more meaningful than a well-intentioned 59 from someone who had to ask for your prefix six times before he gave you the perfect report!

So, here's the result of putting out 5W - quite a lot by WSPR standards - into my delta loop on 20m for more or less a complete day during mid-December 2012. I was especially happy to be picked-up by WA2YUN on Wake Island in the north Pacific - somewhere I previously had never heard of but now know a lot about:

A day of WSPRing.  Most VK/ZL, but certainly not all, was via the Long Path, as was Wake Island. The thicker the lines, the longer contact was maintained.

VA3AQB Guest Post - A 15m Moxon Antenna Project

My Canadian friend, Alan, VA3AQB, has recently been busy making a rather fine version of a Moxon rectangle antenna.  He just about beat the onset of wintry weather, and already, we've managed an easy QSO on 15m using his lovely antenna, which came out ahead, by about an S-point, of his commerical hybrid quad on the day of the test.

Here is how Alan went about it, which includes material kindly provided and approved by KG4JJH:

15m Moxon Project

WSPR Around The World.

WSPR is one of those things that I kept coming across, but knew little about.  In fact, I had no idea other than it was some kind of beacon mode, and I knew nothing about those, either.

Then, one day, the penny dropped.  I was looking into JT65, another weak signal digital mode, and then came across WSPR in the same software package known as WSJT.  For WSPR, though, I use the standalone package for that mode, known simply as WSPR (free).

Screen shot, showing WSPR signal waterfall.

The main problem at this station for some time has been the lack of a proper digital interface.  I decided last week that enough was enough, and took the plunge with Neil, G4ZLP's USB interface, which really is hand made, and got me running on all the digital modes in less than 25 minutes from opening the box and having no previous digital experience at all.

The only problem I did come across was signal stability, which is very demanding for digital modes - just +/- 1Hz is the ideal, and beyond 4Hz, the software will struggle to decode the signal.  My TS480 is pretty stable, but only if it doesn't run too hot or cold; it needs to settle down into an undemanding routine of sending some, listening more (which is how WSPR is meant to work, anyway).  It's changes in the crystal temperature that are the problem, not which temperature it's at per se.  Too much on and offing of the cooling fan introduces big swings in the stability of the reference crystal; I won't be forking out even more money for a temperature-compensated one, which is anyway not perfect.  In practice, swings of +/-3Hz don't seem to affect the received coverage much, but I now have it down to about -1Hz, which is more than acceptable, given the equipment.

Getting out on 20 metres and above is no problem; a multiband, 4:1-fed delta loop cut nominally for 20m works a treat.  But 30 and more especially 40m were not so good, as I had to rely on an end-fed vertical that struggled to get out well on low power, and it is a very noisy antenna on 40m.

The spark of inspiration then hit me.  All those hours of reading antenna literature paid off.  If I can't and don't want to put up a 20m-long dipole for 40m, why not put up a half-delta loop?  This is just 1/6 wave high - an old and partly broken fishing/crappie/squid pole does the job for me - and 1/3 wave as a sloping horizontal section to the ground.  The antenna is grounded into copper water pipe sections driven into our superb ground, fed with coax into a balun or other common-mode busting device.

That's all there is too it.  Earth connections are to copper pipes or rods that provides the other half of the antenna, but use a 1:1 balun or ferrites for the coax!

We all know about antenna images, but it all seems somehow unlikely, somehow unreal.  But I can tell you that reality proves the theory!  Within a few minutes, my 4W signal was reaching Australia during the evening - something I could only dream about with my vertical on 40m.  The noise level for the band has crashed, and now I can clearly hear real 40m SSB DX signals from antipodean points.  Over the next few days, I'll try to talk to them, as well!

So there you go.  Full delta loop performance, with low-angle DX pattern for 40m (matches up on higher bands, too), for half the wire, half the space, and no stupidly-tall vertical structures to contend with.  Who couldn't do with an antenna like that?